DUBAI, Feb 21 (Reuters) - A wave of buying in beaten down blue-chip stock Emaar Properties boosted the Dubai market on Wednesday while most of the region traded quietly in modest volumes.

Dubai's index firmed by 0.5 percent, but remains the Gulf's worst-performing index this year with a decline of 2.5 percent, partly because of a sustained slump in the emirate's real estate market.

However, the bourse was lifted on Wednesday as Emaar, which had been trading near 14-month lows, surged by 3.2 percent to 6.22 dirhams in its heaviest volume this year. It is still down nearly 5 percent since the start of the year.

The increase in volume suggested that some funds were buying back stock on valuation grounds. It had reached a trailing price-earnings ratio of about 7.6 times, according to Thomson Reuters data. That is not expensive by the standards of several Asian markets, where real estate stocks are at multiples of 9-12 times earnings.

Of 12 analysts rating Emaar Properties, 10 have a "buy" or "strong buy" rating and none have a "sell," Thomson Reuters data shows. Their median target for the stock is 9.45 dirhams.

The Saudi Arabia index was flat in its lowest volumes this year. Najran Cement fell 3.8 percent after it swung to an annual net loss of 21.9 million riyals ($5.8 million) from a profit of 125.7 million riyals.

The bank's parent, Qatar National Bank, said this week that it would sell a 2.125 percent stake in QNB Alahly to comply with Cairo listing rules on free floats. The bank has slightly more than 890 million shares outstanding.